The present invention relates to an apparatus for cleaning a wafer and, more particularly, to an apparatus that may improve the cleaning effect without increasing the amount of solvent used.
As device density in a semiconductor ICs increases control over the semiconductor process conditions is increasingly crucial. In VLSI fabrication, the accurate control of layer thickness, reaction temperature, and pressure is more important for reducing defects in semiconductor ICs. Many materials that are used in semiconductor processes undergo, for example, etching, patterning, and planarization processes after the materials are formed on the semiconductor wafer. Before processes are carried out in a reaction chamber, the wafer will be sent to chemical stages for cleaning of the wafer. The unwanted particles will typically be removed from the wafer during these stages.
FIG. 1 shows, in schematic form, a conventional apparatus 10 for removing and cleaning unwanted particles formed on a semiconductor wafer""s surface. The apparatus 10 is used during a cleaning step. The apparatus 10 includes a rotation table 12 for supporting a wafer 14, and a rotation device 16 to rotate the rotation table. A nozzle 18 is set at top of the wafer 14 to spray cleaning solvent on the surface of the wafer 14. A resistance wall 20 located surrounding the apparatus 10 is used to prevent the spun out cleaning solvent from polluting the cleaning room. A liquid outlet 22 is located at the bottom of the resistance wall 20 for draining the waste cleaning solvent out of the resistance wall 20.
During the cleaning step, the nozzle 18 sprays cleaning solvent on the surface of the wafer 14 to remove some of the unwanted particles generated on the wafer 14 during the semiconductor processes described above. At this time, the rotation device will rotate the rotation table 12 and wafer 14 according to the predetermined rotation velocity. The kind of rotation will generate centrifugal force to push the cleaning solvent sprayed on the wafer 14 to clean the wafer 14. After the cleaning step, the cleaning solvent will drain by opening the liquid outlet 22. However, because of only utilizing the centrifugal force to push the cleaning solvent away from the wafer to clean the wafer 14, the conventional cleaning apparatus 10 fails to remove a significant amount of the particles especially some particles adhering to the wafer surface tightly. However, the cleaning solvent will be spun out rapidly in the conventional cleaning apparatus 10, therefore, the cleaning solvent may not stay on the wafer for a long time, which may cause wasteful use of the cleaning agent.
In accordance with the background of the invention, the conventional cleaning method utilizing the centrifugal force to push the cleaning solvent away from the wafer in order to clean the wafer will create many drawbacks. Therefore, the present invention provides an apparatus for performing a wafer cleaning that substantially increases the efficiency of the chemical cleaning process without increasing the quantity of cleaning solvent, and reduces contamination to a clean room in fabricating VLSI circuits.
In one embodiment, the present invention includes a rotating table supporting the wafer, a rotation device to rotate the rotation table, a movable or stationary curved-slab for scrubbing the surface of the wafer efficiently, a cleaning nozzle for applying a cleaning solvent or stripper on the surface of the wafer, and a resistance wall for preventing the spun out cleaning solvent from polluting the cleaning room.